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Only lower "addi sp, sp, X" if X > 0.

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If X < 0, then lowering the addi might cause the code to use the stack
space before allocating it.  This is a bug because an asynchronous
signal handler can overwrite the unallocated stack space.
This commit is contained in:
George Koehler 2018-02-01 12:20:31 -05:00
parent 9077b3a5ab
commit 04ac91889c
1 changed files with 23 additions and 13 deletions
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36
mach/powerpc/top/table
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@ -8,6 +8,7 @@ LABEL_STARTER '.';
L1, L2, L3, L4, L5 { not_using_sp(VAL) };
RNZ { strcmp(VAL, "r0") }; /* not r0 */
UP { positive(VAL) };
X, Y, Z { TRUE };
%%;
@ -20,22 +21,22 @@ addis RNZ, RNZ, 0 -> ;
addi RNZ, RNZ, X : addi RNZ, RNZ, Y { plus(X, Y, Z) }
-> addi RNZ, RNZ, Z ;
/* Lower "addi sp, sp, X" by lifting other instructions, looking for
/* Lower "addi sp, sp, UP" by lifting other instructions, looking for
* chances to merge or delete _addi_ instructions, and assuming that
* the code generator uses "sp" not "r1".
*/
addi sp, sp, X : ANY L1 { lift(ANY) }
-> ANY L1 : addi sp, sp, X ;
addi sp, sp, X : ANY L1, L2 { lift(ANY) }
-> ANY L1, L2 : addi sp, sp, X ;
addi sp, sp, X : ANY L1, L2, L3 { lift(ANY) }
-> ANY L1, L2, L3 : addi sp, sp, X ;
addi sp, sp, X : ANY L1, L2, L3, L4 { lift(ANY) }
-> ANY L1, L2, L3, L4 : addi sp, sp, X ;
addi sp, sp, X : ANY L1, L2, L3, L4, L5 { lift(ANY) }
-> ANY L1, L2, L3, L4, L5 : addi sp, sp, X ;
addi sp, sp, X : lmw Y, L1 { Y[0]=='r' && atoi(Y+1)>1 }
-> lmw Y, L1 : addi sp, sp, X ;
addi sp, sp, UP : ANY L1 { lift(ANY) }
-> ANY L1 : addi sp, sp, UP ;
addi sp, sp, UP : ANY L1, L2 { lift(ANY) }
-> ANY L1, L2 : addi sp, sp, UP ;
addi sp, sp, UP : ANY L1, L2, L3 { lift(ANY) }
-> ANY L1, L2, L3 : addi sp, sp, UP ;
addi sp, sp, UP : ANY L1, L2, L3, L4 { lift(ANY) }
-> ANY L1, L2, L3, L4 : addi sp, sp, UP ;
addi sp, sp, UP : ANY L1, L2, L3, L4, L5 { lift(ANY) }
-> ANY L1, L2, L3, L4, L5 : addi sp, sp, UP ;
addi sp, sp, UP : lmw Y, L1 { Y[0]=='r' && atoi(Y+1)>1 }
-> lmw Y, L1 : addi sp, sp, UP ;
/* Merge _addi_ when popping from the stack. */
addi sp, sp, X : lwz L1, Y(sp) { plus(X, Y, Z) && Z[0]!='-' }
@ -117,6 +118,15 @@ int not_using_sp(const char *s) {
}
int positive(const char *s) {
long n;
char *end;
n = strtol(s, &end, 10);
return *s != '\0' && *end == '\0' && n > 0;
}
/* Instructions to lift(), sorted in strcmp() order. These are from
* ../ncg/table, minus branch instructions.
*/